Laser drilling systems for drilling holes in medical devices are known in the art. The laser drilling systems are often used to drill blind holes in the proximal ends of surgical needles. Conventional surgical needles typically have a suture mounting end to which a surgical suture is mounted. The proximal end may have a channel or a blind bore hole to receive the distal end of a surgical suture, which is then affixed to the needle mounting section using conventional techniques such as mechanical swaging, gluing, adhesives, etc. There is a preference for using needles having drilled blind bore holes versus channels. The needles having drilled bore holes tend to have a more regular profile after suture attachment when compared with surgical needles having a channeled mounting end. It is also possible to more closely match up the needle diameter with the diameter of the attached suture. This provides the advantage of having better perceived movement through tissue and less tissue drag, and a more narrow tissue pathway, potentially providing a superior clinical outcome such as improved hemostasis. On the other hand, channeled suture needles are more economical to produce.
A blind bore hole is typically drilled into the proximal end of a surgical needle using conventional methods including mechanical drilling and laser drilling. Although mechanical drilling may provide for a precisely drilled bore hole having a uniform configuration, it is known that mechanical drilling may have deficiencies associated with its use. Mechanical drilling requires drills that have a fine diameter in order to drill surgical needles having fine needle sizes, such as sizes 0.15 mm (0.006 in). Such drills are difficult to manufacture in fine diameter sizes and tend to wear out relatively quickly in a high speed production process. In addition, because of the fine wire sizes of the needles, and the fine diameters of the needle, the precision mechanical drilling equipment may require frequent downtime in order to precisely adjust and align the drills. Laser drilling systems overcome these deficiencies by providing high speed drilling capabilities without the need for expensive drills. In addition, there is minimal downtime for adjustments once the system has been set up. Another advantage of laser drilling systems is the ability to easily switch between the drilling of various needle wire diameters having different bore hole diameters and lengths.
Nd-YAG laser systems useful for drilling blind boreholes in surgical needles are disclosed in U.S. Pat. No. 6,252,195 and U.S. Pat. No. 6,683,276, both of which are incorporated by reference. These patents disclose diode pumped Nd-YAG laser drilling systems for surgical needles. The oscillator in these systems is diode pumped, and the amplifiers are diode pumped as well. High speed surgical needle manufacturing processes are described in U.S. Pat. Nos. 5,630,268, 5,644,834, 5,661,893, 5,701,656, 5,776,268, 5,913,875, 6,018,860, and 6,252,195, which are incorporated by reference. Such manufacturing processes, which process a surgical needle from a spool of wire to a surgical needle blank to a finished surgical needle, typically mount the needle blanks to a carrier strip, wherein in the strip and needle blanks are moved through progressive forming and processing stations to produce a finished surgical needle.
However, there are certain disadvantages associated with the laser drilling of surgical needles using conventional laser systems. In order to drill a bore hole of the desired diameter and depth in a structure such as the proximal end of a surgical needle, it is necessary to have a beam of sufficient power and quality. In addition, the laser drilling process is a percussive drilling process wherein a laser beam is chopped into a series of pulses. Percussive drilling is necessary since the drilling process produces molten and vaporized metal that is ejected out of the bore hole during the process. Accordingly, blind bore holes that are laser drilled typically tend to not have a perfectly symmetrical configuration. This can be an issue in suture attachment, especially with high speed automated systems. The geometry of the drilled bore hole may vary over time requiring frequent and precise quality assurance inspections, and associated laser and production downtime to adjust the laser system to bring the drilled bore holes into conformance with manufacturing specifications. In addition, variations in the laser beam parameters may result in deficiencies such as recast. Recast may affect the ability of the proximal end of a surgical needle having a laser-drilled borehole to be mechanically swaged in order to attach an end of a surgical suture without cracking the metal about the bore hole. Another deficiency that may be associated with conventional laser drilling systems for surgical needles is the inability to readily and easily drill a variety of different sizes of surgical needles. Currently available systems are typically set up to drill a narrow range of hole diameters, e.g., small boreholes, medium or large. Also, it is known that in order to drill acceptable bore holes in medium and larger diameter needles, it is typically necessary to apply an ink coating to the proximal end of the needle. This ink coating allows for more effective energy absorption and beam coupling. Typically, it is very difficult and impractical to drill the medium to large diameter needle sizes without this inking operation, which adds a level of complexity and increased costs to the manufacturing process.
There is a need in this art for novel laser drilling systems that provide superior performance with minimal downtime for adjustments. There is also a need for novel laser drilling systems for surgical needles that have high quality beams which provide high quality laser-drilled bore holes for suture mounting. In addition, there is a need for novel laser drilling systems for surgical needles that can precisely drill a variety needle wire sizes and that can be readily and easily adjusted to switch between wire sizes.